Maize Root system iTRAQ result under salt treatment

To acknowledge the molecular mechanisms underlying maize salt tolerance, two maize inbred lines, including salt-tolerant 8723 and salt-sensitive P138, were used in this study. Comparative proteomics of seedling roots from two maize inbred lines under 180 mM salt stress for 10 days was performed by the isobaric tags for relative and absolute quantitation (iTRAQ) approach. We obtained a total of 336237 spectra. 30616 peptides and a total of 7505 proteins were identified with 1% FDR. A total of 7505 differentially expressed proteins (DEPs) were identified. 626 DEPs were identified in line 8723 under salt stress, among them, 378 up-regulated and 248 down-regulated. 473 DEPs were identified in P138, of which 212 were up-regulated and 261 were down-regulated. Venn diagram analysis showed that 17 DEPs were up-regulated and 12 DEPs were down-regulated in the two inbred lines. In addition, 8 DEPs were up-regulated in line 8723 but down-regulated in P138, 6 DEPs were down-regulated in line 8723 but up-regulated in P138. In salt-stressed 8723, the DEPs were primarily associated with phenylpropanoid biosynthesis, starch and sucrose metabolism, and the MAPK signaling pathway. Intriguingly, the DEPs were only associated with the nitrogen metabolism pathway in P138. Compared to P138, the root response to salt stress in 8723 could maintain stronger water retention capacity, osmotic regulation ability, synergistic effects of antioxidant enzymes, energy supply capacity, signal transduction, ammonia detoxification ability, lipid metabolism, and nucleic acid synthesis. Based on the proteome sequencing information, changes in the abundance of 8 DEPs were correlated with the corresponding mRNA levels. Our results from this study may elucidate some details of salt tolerance mechanisms and salt tolerance breeding of maize.